Electromagnetic relay and process for producing the same

ABSTRACT

The relay comprises a first housing part in which a coil having a U-shaped core is embedded, as well as a second housing part in which at least one spring support as well as at least one mating contact element are anchored. A contact spring with a flat armature is attached to the spring support. The relay is adjusted and additionally sealed by joining the two half-shells.

BACKGROUND OF THE INVENTION

The invention relates to an electromagnetic relay having

a first housing part, which is fitted with a coil as well as a corewhich passes through the coil and, outside the coil, forms pole platesat its two ends,

a second housing part in which at least one spring support and at leastone mating contact element are anchored, the spring support being fittedwith a contact spring which interacts with the mating contact element,and

an armature which is connected to the contact spring and bridges thepole plates forming air gaps.

In addition, the invention relates to a method for producing such arelay.

EP 0 531 890 A1 describes a switching relay which is in principleconstructed in the manner described initially. There, however, the twohousing parts do not form a closed housing but only a base which ispreferably a printed circuit board having an integrally formed sidewall, and a cover part between which a large housing gap remains openeven after the two parts have been joined together. The relay ispreferably designed as a multiple relay having a row of magnet systemslocated alongside one another, a common core pole plate being located onthe base and forming a row of vertically projecting core sections ontoeach of which a coil is fitted. Each system also has a U-shaped armaturewhich is mounted on a core pole plate and, with the contact spring,encloses the coil like a frame. The cover part has slits with insertedmating contact elements and spring supports, and these slits likewiseare not sealed. There, the contacts are clearly adjusted through thelarge housing opening in the region of the contacts.

WO 91/07770 has already disclosed a relay in which the magnet system isfixed in the upper region of a housing, while a contact system is pushedin from the open underneath until the contact closes when the magnetsystem is energized. Once this contact system has been pushed in furtherby a predetermined amount in order to produce a desired overtravel, itis fixed in the housing. This allows manufacturing tolerances to becompensated for even at the assembly stage, so that there is no longerany need for a subsequent adjustment.

DE-A-2 506 626 discloses a contact support for switching elements, whichcontact support can be closed by a housing and is composed of adielectric. Armature contacts are mounted either in a glass tube or in aplastic frame as a support, and this support is closed on the outside bytwo housing caps. All the moving parts are housed there in one and thesame support part, while the housing caps have no influence on thepositioning of the functional elements of the relay.

EP-A-0 251 035 furthermore discloses a relay which comprises two basebody parts which are in the form of half-shells, form a coil former andare fitted with the winding. Two pole plates are embedded in a commonplane in one of the base body parts, and their ends are bridged in acontact space within the coil by means of an armature contact. Thearmature itself is fixed by a spring, in the form of a frame, which isin the separating plane between the two base body parts.

SUMMARY OF THE INVENTION

The aim of the present invention is to provide a relay of the typementioned initially and having a flat design, which is designed fordifferent sizes and applications and which can be produced in largequantities very cost-effectively, using the appropriate manufacturingmethods. At the same time, a high degree of accuracy is intended to beachieved as early as the manufacturing stage by virtue of the design, sothat the relay characteristics are maintained with only smalltolerances, even without subsequent adjustment.

This aim is achieved according to the invention in the case of such arelay in that the two housing parts, which are joined together at theiredges to form a seal, are roughly trough-shaped half-shells made ofplastic, while the connections for the coil winding and for the contactelements are each passed out through the walls of their respectivehousing parts, and in that the main joint planes between the two housingparts are at right angles to the switching movement of the contactspring.

In the case of the relay according to the invention, the two half-shellsnot only form a housing which is easy to seal, but they are also used assupport for the functional elements of the relay, and these functionalelements, that is to say the magnet system in the one part and thecontact system in the other part, can be positioned very accurately asearly as during the manufacture of the respective half-shell. The mainjoined planes between the two housing parts are preferably at rightangles to the switching movement of the contact spring, so that thedistance between the magnet system and the contacts can be adjusted bythe joining together of the two housing parts. The fixing of thefunctional parts in the housing and the sealing of the connections areachieved particularly easily by embedding them in the respective housinghalf-shell. The joint planes are composed of plastic, preferably athermoplastic, so that a sealed connection can be produced, for exampleby means of ultrasound, in a simple manner.

In one preferred embodiment, the magnet system is formed by a U-shapedcore yoker plate, which is preferably embedded in a plastic coil formerin the same way as at least two coil connections. The pole plates whichare formed at the two ends of the core then extend at right angles tothe core axis in the region alongside the coil, where they are bridgedby an armature which is located alongside the coil. This armature may bedesigned to a greater or lesser extent as a flat metal sheet or may bebent at different levels at the two ends in order to interact with thepole plates, which are likewise correspondingly offset in height. Thismakes it possible to optimally utilize space in the housing toaccommodate the contacts and the various connections. An L-shapedcontact spring has one limb which extends at the end in front of thecoil and the other or second limb which extends alongside the coilunderneath or above the armature, and this structure results in a longspring length in a confined space. The armature is preferably attachedto the contact spring in the transition region between the two springlimbs.

A preferred method for producing the relay, according to the invention,comprises the first housing part being produced by embedding the coilwith the core including the coil connections, by the second housing partbeing produced by embedding the spring support and at least one matingcontact element, by the contact spring, which is connected to thearmature, being connected to the spring support, and by the edges of thetwo housing parts then resting on one another and being connected. Inthis case, the coil former is preferably also formed in advance byembedding the core and the coil connections, the first housing partbeing produced by a second embedding process after the winding of thecoil and after the connection of the coil ends to the coil connections.Before the two housing parts are joined together, the armature isconnected to the contact spring, an electrically conductive connectionbeing possible by welding or the like, or an insulating connection bymeans of extrusion coating, depending on the application. The contactspring is then electrically conductively attached to the spring supportwhich is anchored in the second housing part, for example by welding orelse via a plug-in attachment.

A major advantage of the invention may also be regarded as being thatthe contact overtravel can be adjusted during the process of joining thetwo housing parts in that, the seal-in voltage of the armature ismeasured for example during the joining process, and the joining processis then interrupted when a predetermined seal-in voltage electricalcharacteristic is. This characteristic is a measure of the amount oferosion or the overtravel of the contact. Instead of being connected byultrasound or some other welding method, the two half-shells canalternatively be sealed using other technologies, for example bybonding, clamping, potting or by means of an elastomer seal which ismolded on using a two-component injection-molding method.

The invention will be explained in more detail in the following textusing exemplary embodiments and with reference to the drawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a relay designed according to the invention, with thehousing partially cut away,

FIG. 2 shows a coil for the relay in FIG. 1,

FIG. 3 shows a first half-shell which is produced by extrusion coatingof the coil,

FIG. 4 shows a second half-shell with the armature inserted,

FIG. 5 shows a plan view of the second half-shell of FIG. 4, without thearmature,

FIG. 6 shows an armature welded to a contact spring,

FIG. 7 shows an armature connected to the contact spring by an extrusioncoating,

FIG. 8 shows a plan view of the second half-shell with the armature andwith the contact spring fitted,

FIG. 9 shows a cross sectional view taken along line IX—IX of FIG. 8,but with a first half-shell additionally fitted,

FIG. 10 shows a relay somewhat modified from that in FIG. 1, during theprocess of joining the two half-shells, and

FIG. 11 shows a further modification of the relay of FIG. 1 with adifferent connection configuration.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The relay shown in FIGS. 1 to 5 comprises a first half-shell 1 and asecond half-shell 2. The half-shell 1 is formed by extrusion coating ofa coil 3, and the second half-shell is formed by extrusion coating of aspring support 21 as well as mating contact elements 22 and 23. AnL-shaped contact spring 4 is attached to the spring support 21 and, forits part, is fitted with an armature 5. Each of the ends of the armature5, which is bent roughly in a Z-shape, forms an air gap with two polesurfaces 63 and 64 of the pole plates 61 and 62, which are part of aU-shaped core 6, but in which case the pole plate or core 6 and plate 6162 is bent upward out of the core plane.

During manufacture, the coil is produced first of all by extrusioncoating the center section of the core 6 with a thermoplastic, thusforming a coil former 31. The pole plates 61 and 62 are kept free duringthis process. Furthermore, two coil connections 32 and 33 are moldedinto the coil former, to be precise such that not only the connectingpins 32 a and 33 a which point outward but also the inner connectingsurfaces 32 b and 33 b, which are intended to make contact with thewinding ends, remain free of the embedding agent. After a coil winding34 has been fitted on the coil former, the ends of the winding areconnected to the connecting surfaces 32 b and 33 b. The winding ends arein this case routed such that they are protected behind ribs 35 inchannels 36 in the coil former. The entire coil is then once againextrusion coated, in order in this way to produce the first half-shellaccording to FIG. 3. The pole surfaces 63 and 64 of the pole plates 61and 62 also remain free of this extrusion coating, while the otherparts, in particular the coil winding 34 as well, are embedded in theplastic 11 of the first half-shell 1. The coil connecting pins 32 a and33 a are passed to the outside in a sealed manner in this repeatedembedding process, where, according to FIG. 1 or FIG. 3, they can bebent downward into the shape of the pins 32 and 33 or, in a manner notillustrated, they can also be bent in a horizontal plane in order toform connections for surface-mounted devices.

As already mentioned, the second half-shell 2 is produced by extrusioncoating of the spring support 21 and the mating contact elements 22 and23, with a cavity being left free for the coil and the movingarmature/contact spring unit. In this case, each of the mating contactelements has a connecting pin 22 a or 23 a, respectively, which isrouted in a sealed manner to the outside, while fixed contact sections22 b and 23 b, respectively, in the interior are each provided with anoble-metal contact layer 22 c or 23 c (see FIG. 9), respectively. Inthe present example, the contact material is plated as an inlay into thesurface of the respective contact element, so that it can easily becovered by extrusion coating. Otherwise, different technologies forapplying the contact material would also be conceivable. Instead of thetwo mating contact elements 22 and 23, only one mating contact elementcould, of course, also be provided in order to form a break contact or amake contact.

The contact spring (FIG. 4), which is an L-shaped design, has a firstspring limb 41 which extends at the end in front of the coil, as well asa second spring limb 42, which extends at the side alongside the coilunderneath the armature and is fitted with a moving contact 43 (FIG. 6or FIG. 9). The first spring limb 41 is attached via a fastening lug 44,which is bent upward, to the spring support 21 via a welded joint 46according to FIG. 4 or via a clamping claw 45 according to FIG. 8. Thisconnection technique means that the height at which the contact spring 4is mounted on the spring support 21 is variable, which also means thatit is possible to adjust the position of the second spring limb 42 withrespect to the mating contact elements. In this way, it is possible toinfluence the armature restoring force and the force when the contact isin the rest state, during the assembly process, in order to compensatefor the tolerances.

Before attaching the contact spring to the spring support 21, it isconnected to the armature 5, which can be done in an electricallyconductive manner, for example according to FIG. 6, via a welded joint51. If there is intended to be insulation between the contact spring andthe magnet system, then the connection can be produced by a dielectricsheath 52 according to FIG. 7. For certain applications, it is alsopossible for the current to the contact spring to be carried via abraid. Thus, for example, higher control levels can be carried via sucha braid with low resistance to the contact point, in order to avoidexcessive heating of the spring.

When the two half-shells 1 and 2 (see FIG. 9) are being joined together,a circumferential wall 12 engages like a box lid over the lower housingpart 2 which, for this purpose, has a web 24 running round on theinside. In order to achieve accurate adjustment of the distances betweenthe magnet system and the contact system, one of the housing parts alsohas a circumferential rib 25 which is deformed by means of ultrasoundduring the joining process and produces the sealed connection betweenthe two half-shells. In this case, the seal-in voltage of the armatureis measured while the two half-shells are being joined, the armaturebeing attracted to the pole surfaces 63 and 64 of the pole plates 61 and62. As soon as the seal-in voltage reaches a predetermined level as ameasure of the amount of erosion or the overtravel of the contact, thejoining process is ended. The relay is thus adjusted and at the sametime sealed.

FIG. 10 shows a variant of the relay from FIG. 1. In this case, the twohalf-shells 101 and 102 are not connected in a single joint plane, butwith mutually stepped joint planes 103 and 104. The internalconstruction of the relay is the same as in the previous example, apartfrom the fact that a mating contact element, namely a make-matingcontact plate 105 is molded with its connecting pin 105 a into the firsthalf-shell with the magnet system. In this case, the distance betweenthe mating contacts can be influenced during the process of joining thetwo half-shells. In this variant, an injection-molding mold without aslide can be used to provide both welded, riveted and inlay contacts onthe mating contact elements.

By virtue of the use of relatively flat parts, the construction of therelay also permits other embodiments of the connection geometry, so thatthe connections can also emerge from the housing on only one relay side.Such an option is shown in FIG. 11, in which case a first half-shell 110is fitted with the contact elements with connecting pins 111, 112 and113, and a second half-shell 120 is fitted with the magnet system withthe coil connecting pins 121 and 122. Such a relay requires only a smallbase area for plugging in or for soldering. A blader plug could, ofcourse, also be provided instead of the solder connecting pins in FIG.11. As has already been mentioned earlier, the connecting pins are, ofcourse, also designed as SMD connections for surface mounting.

What is claimed is:
 1. An electromagnetic relay comprising a firsthousing part, which is fitted with a coil having a core with two endsextending through the coil with the two ends forming two pole platesoutside of the coil, a second housing part having at least one springsupport and at least one mating contact element anchored therein, thespring support being fitted with a contact spring which interacts withthe mating contact element and an armature which is connected to thecontact spring and bridges the pole plates forming air gaps, each of thetwo housing parts being half-shells made of plastic and having a basewith upstanding walls with edges, said two housing parts being joinedtogether at the edges of the walls to form a sealed housing withconnections for the coil windings and for the contact elements passingout through the walls of said respective housing parts and a main jointplane between the two housing parts extending at right angles to aswitching movement of the contact spring, the coil including a coilformer with a coil winding being embedded together with a portion of thecore in the plastic of the first housing part with pole surfaces of thepole plate in the region of the air gaps being free of the plastic, andthe spring support and at least one mating contact element beingembedded in the plastic of the second housing part.
 2. A relay accordingto claim 1, wherein the core is embedded in a plastic of a coil former.3. A relay according to claim 2, wherein connecting elements for thecoil winding are embedded both in the coil former and in the plastic ofthe first housing part.
 4. A relay according to claim 1, wherein thecoil has a coil axis and the core is U-shaped with a center sectionbeing fitted within the coil and the two pole plates projecting at rightangles to the coil axis from one side of the coil, and the armatureextending parallel to the coil axis on the one side of the coil with thetwo pole plates.
 5. A relay according to claim 4, wherein the contactspring is cut in an L-shape, so that it has two limbs which lie in oneplane, a first limb of the two limbs extends to an end of the coil and asecond limb of the two limbs extends alongside the one side of the coil,said second limb and the armature being located in a stack and beingconnected in a corner region between the two limbs of the contactspring.
 6. A relay according to claim 5, wherein the armature isconnected to the spring via a common dielectric sheath.
 7. A relayaccording to claim 1, which includes two mating contact elements beinganchored in the second housing part and forming a changeover contactwith the contact spring.
 8. A relay according to claim 1, wherein asecond mating contact element is anchored in the first housing part andforms a changeover contact with the mating contact element in the secondhousing part and with the contact spring.
 9. A method of producing arelay which has a first housing part with a coil having a core passingthrough the coil with outer ends of the core forming pole plates beinganchored in the housing part, a second housing part having anchoredtherein at least one spring support and at least one mating contactelement, the spring support being fitted with a contact spring whichinteracts with the mating contact element and an armature beingconnected to the contact spring and bridging the pole plates forming airgaps, the method comprising the steps of producing the first housingpart by embedding the coil with the core including coil connectionstherein; producing the second housing part by embedding the springsupport and said at least one mating contact element therein, each ofthe housing parts being formed as trough-like half-shells with a basehaving upstanding walls with edges forming at least one main joint planewhich extends at right angles to the movement direction of the armature,so that the contact spring which is connected to the armature isconnected to the support structure; and then joining the edges of twohousing parts to one another to complete a housing for the relay.
 10. Amethod according to claim 9, which includes providing the coil with thecore by embedding the core and the coil connections in a coil former,providing a coil winding on the former and then embedding the coilformer with the coil winding in order to form the first housing part.11. A method according to claim 9, which includes welding the armatureto the contact spring and connecting the contact spring to the springsupport.
 12. A method according to claim 9, wherein the armature isconnected to the contact spring by a dielectric sheath.
 13. A methodaccording to claim 9, wherein the contact spring is connected to thespring support by welding.
 14. A method according to claim 9, whereinthe contact spring is connected to the spring support by plug-inattachment.
 15. A method according to claim 9, wherein the step ofjoining the two housing parts together includes measuring armaturetravel and/or overtravel and ending the joining process when apredetermined magnitude is reached.
 16. A method according to claim 15,wherein edge regions of at least one of the two half-shells is deformedduring the joining process until a predetermined overtravel is reached.17. A method according to claim 16, wherein the step of forming one ofthe two half-shells provides a rib along the edge of the half-shell andthe step of deforming the edge region includes deforming the rib byultrasound during the joining process.
 18. A relay according to claim 5,wherein the armature has a metallic connection to the contact spring,said connection being selected from a welded connection and a rivetedconnection.
 19. A relay according to claim 1, wherein the walls of thetwo housing parts have different heights so that the edges of the wallslie in parallel offset planes.